Adult myocardial cells have no proliferative capacity. Hence, once damaged myocardium remains unrepaired, patients develop heart failure with a permanent malfunction. As arteriosclerotic vascular diseases increase due to the aging of population and westernized lifestyle habit, the number of heart failure patients is increasing. Particularly in the case of severe heart failure such as ischemic cardiomyopathy, by which remaining cardiac stem cells disappear due to frequent myocardial infarction, medical treatment has not been sufficiently effective. Also, blood flow improved by PCI (coronary angioplasty) and coronary artery bypass surgery has only a limited effect. The annual death rate at the end stage of severe heart failure that is refractory to these treatments is considered to be about 75%. Development of novel therapeutic methods and pharmaceutical products is expected.
Patent Literature 1 discloses a method for preparing myocardial grafts by culturing ES cells during induction of differentiation in the presence of a polyamine such as spermine. Cells after treated with spermine are pace maker-like myocardial cells, into which the differentiation has been induced.
Patent Literature 2 discloses a method for forming a cell sheet containing cardiac myoblast cells, wherein the method comprises: culturing adipose tissue-derived stem cells in the presence of DMSO, or an OP9 culture supernatant, to differentiate into cardiac myoblast cells; and forming a cell sheet containing the cardiac myoblast cells.